The small SLC43 family: Facilitator system l amino acid transporters and the orphan EEG1

• Published in: Molecular aspects of medicine 2013-04, Vol.34 (2-3), p.638-645
• Main Authors: Bodoy, Susanna, Fotiadis, Dimitrios, Stoeger, Claudia, Kanai, Yoshikatsu, Palacín, Manuel
• Format: Article
• Language: English
• Subjects: Amino Acid Transport System y+L - genetics; Amino Acid Transport System y+L - metabolism; Amino Acid Transport System y+L - physiology; Amino Acid Transport Systems - metabolism; Amino Acid Transport Systems, Basic - metabolism; Amino Acids - metabolism; Blotting, Northern; EEG1; Humans; l-type amino acid transporter; LAT3; LAT4; Liver - metabolism; Mechanistic Target of Rapamycin Complex 1; Models, Molecular; Multigene Family - genetics; Multiprotein Complexes - metabolism; Muscle, Skeletal - metabolism; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Neoplasm Proteins - physiology; Podocytes - metabolism; SLC43; TOR Serine-Threonine Kinases - metabolism
• ISSN: 0098-2997; 1872-9452
• DOI: 10.1016/j.mam.2012.12.006

The SLC43 family is composed of only three genes coding for the plasma membrane facilitator system l amino acid transporters LAT3 (SLC43A1; TC 2.A.1.44.1) and LAT4 (SLC43A2; TC 2.A.1.44.2), and the orphan protein EEG1 (SLC43A3; TC 2.A.1.44.3). Besides the known mechanism of transport of LAT3 and LAT4, their physiological roles still remain quite obscure. Morphants suggested a role of LAT3 in renal podocyte development in zebrafish. Expression in liver and skeletal muscle, and up-regulation by starvation suggest a role of LAT3 in the flux of branched-chain amino acids (BCAAs) from liver and skeletal muscle to the bloodstream. Finally, LAT3 is up-regulated in androgen-dependent cancers, suggesting a role in mTORC1 signaling in this type of tumors. In addition, LAT4 might contribute to the transfer of BCAAs from mother to fetus. Unfortunately, the EEG1 mouse model (EEG1Y221∗) described here has not yet offered a clue to the physiological role of this orphan protein.